Patent literature 1 discloses an example of an LED package to which an LED chip having a back electrode is used. In the LED package, a conductive pattern for mounting and a conductive pattern for bonding a bonding wire are formed on an insulating substrate. The back electrode of the LED chip is bonded to the mounting conductive pattern using a chip bonding material (bonding material). One end of a bonding wire is connected to the bonding wire bonding conductive pattern, and the other end of the bonding wire is connected to the front-side electrode of the LED chip. The die bonding material used therein is a conductive silver paste.
In this case, since the silver paste is a hygroscopic material, when the silver paste is used for chip bonding, the chip bonding material may absorb moisture when using the LED package. If the chip bonding material absorbs moisture, there is concern that the efficiency of the power supplied to the LED chip via the chip bonding material will decrease. Also, since the silver paste has a relatively low electric conductivity, there is a problem that an LED package to which the silver paste is used for chip bonding is not suitable for use in an LED chip of higher output.